Lubricants containing p-polyphenyl



United States Patent LUBRICANTS CONTAINING p-POLYPHENYL Matthew A. McMahon, Jr., Hopewell Junction, and Harry Chafetz and William .I. Coppoc, Poughkeepsie, N.Y.,

assignors to Texaco Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 17, 1964, Ser. No. 411,720

6 Claims. (Cl. 252-42.1)

This invention relates to new oleaginous compositions. More particularly, it relates to lubricating oil and grease base compositions containing a novel extreme pressure agent therefor, namely, poly-p-phenylene of an average molecular weight of at least about 3000. In addition, the invention pertains to a method of lubricating metal surfaces utilizing said poly-p-phenylene and oleaginous compositions.

One of the most popular and widely used extreme pressure agents in lubricating oil and grease base compositions is molybdenum disulfide. Although this is an effective film strength additive, it has the disadvantage of breaking down under high temperature oxidative engine conditions to form corrosive inorganic substances which attack the metal to be lubricated.

An object of the invention is to formulate lubricating oil and grease compositions containing a novel organic extreme pressure agent composed of carbon and hydrogen.

Another object of the invention is to produce lubricating oil and grease compositions containing an extreme pressure additive which will not break down into corrosive inorganic substances.

Still another object of this invention is to provide a method of lubricating metal surfaces employing compositions of good lubricity and extreme pressure properties.

In accordance with the objects of the invention, we have discovered that when polyp-phenylene of the general formula:

where n is an average integer of at least about 38 and up to 200 and higher, is incorporated in a lubricating oil or grease in an amount to impart extreme pressure properties thereto, e.g., between about 0.5 and 30 wt. percent, a significant improvement is imparted to the lubricating oil and grease formulation in respect to extreme pressure (film strength) properties as measured by the standard film strength tests. Further, we have discovered that when the poly-p-phenylene is finely divided it functions alone as an outstanding dry lubricant.

The poly-p-phenylene additive of the invention is a solid polymer and essentially insoluble in lubricating oil and grease composition. It is incorporated into these compositions or employed as a dry lubricant as a finely divided solid advantageously in a particle size between about 2 and 100 microns, preferably between 2 and 10 microns.

The oleaginous compositions of the invention are prepared by any standard means known in the art with the finely divided poly-p-phenylene extreme pressure additive being suitably incorporated during any stage of the preparation, of the final oleaginous composition. However, the polymers normal point of addition is as a final step in the preparation of the lubricant composition. This is suitably accomplished by merely adding the desired quantity of finely divided poly-p-phenylene to the oleaginous base composition at elevated temperature, e.g., between about 100 and 200 C. with stirring in order to facilitate distribution.

The poly-p-phenylene extreme pressure agent is prepared by contacting benzene with aluminum chloridecupric chloride condensing combination at a temperature between about 5 and 80 C. for a period of between about 3,384,588 Patented May 21, 1968 0.25 and 24 hours. Under advantageous conditions the condensing combination constitutes between about 10 and wt. percent of the reaction mixture and the mol ratio of aluminum chloride to cupric chloride is desirably between about 2:1 and 1:1. Further, under preferred conditions the contact is made under agitation conditions with finely divided aluminum and cupric chloride, e.g., of a particle size of less than about 30 microns, desirably from 2 to 10 microns. The formed poly-p-phenylene is a brownish to black colored solid and is recovered by standard means, such as filtration. The recovered brown-black poly-p-phenylene solid is not soluble in any standard solvent such as water, ether, carbon disulfi-de, dimethylformamide, ethanol, ethyl acetate, cyclohexane benzene, and toluene. It has no definite melting point and begins to decompose at a temperature of about 350 C. It is composed of a mixture of repeating phenylene groups in various chain lengths, the average molecular weight of the chains bein at least about 3000. The repeating phenylene groups are primarily in para position to one another although there may be an insignificant amount of ortho branching and cyclization. Further, the polymer may contain impurity (very small) amounts of substituents other than carbon and hydrogen, for example, chlorine which is derived from the condensing agent employed in the polymer preparation. In addition, the polymer is often associated with impurity amounts of inorganic compounds that become encapsulated by the polymer molecules. The poly-p-phenylene polymers are further described in the article by Kovacic et al., Polymerization of Benzene to p-Polyphenyl by Aluminum Chloride-Cupric Chloride, J. Amer. Chem. Soc. 85, pages 454-458 (1963).

In the lubricating oil composition of the invention the base oils may be mineral oils derived from parafiin base, naphthene base, or mixed paraflin-naphthene base distillate or residual oils. Mineral lubricating oils having an SUS viscosity at 100 F, of between about and 10,000 are examples of those suitable in the formulation of the improved lubricating oil compositions of this invention.

Synthetic lubricating base oils are also contemplated. Examples of the synthetic lubricant oils contemplated within the invention are the aliphatic esters of ca-rboxylic acids and alcohols, polyalkylene oxides, silicones, siloxanes, esters of phosphoric and silicic acids and highly fluorine substituted hydrocarbons. Synthetic lubricating oils of a viscosity at F. of between about 50 and 10,000 SUS are among those synthetic oils contemplated.

Specific examples of the aforementioned classes of synthetic lubricating oils are di-2-ethylhexyl sebacate, di-Z- ethylhexyl :adipate, di-3,5,5-triethylhexyl glutarate, di-2- metboxy-Z-ethyl sebacate, pentaerythritol tetracaproate, polyisopropylene oxide, polyisopropylene diether, methyl silicone, methylphenyl, silicone, tetraisooctyl silicate, perfluoroaliphatic hydrocarbons (e.g., C zs, C F C F polymethyl siloxane and trimethyl phosphate. A further description of the contemplated synthetic lubricants is found in Kirk-Othmer, Encyclopedia of Chemical Technology, vol. 8, pages 511-524 (1952).

In addition to the poly-pphenylene extreme pressure additive supplementary additives are normally included in the lubricating oil base material. These supplementary additives are designed to impart other desirable properties to the lubricating oil base, for example, viscosity index (VI) improvers, corrosion inhibitors and detergentdispersants.

A widely used VI improver is a polymeth'acrylate of the general formula:

COOR n where R is an aliphatic radical and n is an integer between about 600 and 35,000. The VI improvers are usually present in the lubricating oil in an amount between about 0.1 and 10 wt. percent. Commonly used detergentdispers'ants are alkaline earth metal phenolates, such as barium nonylphenolate, barium dodecylcresolate, and calcium dodecylphenolate. Other detergents which may be employed are the monohydroxyalkyl hydrocarbyl thiophosphonates such as Z-hydroxyethylpolyisobutene (1100 M.W.) thiophosphonate, 4 hydroxyamylpropylenebutylene co-polymer (1100 M.W.) thiophosphonate and 3- hydroxybutyl polypropylene (1500 M.W.) thiophosphonate. Other desirable dispersants are the interpolymers of alkyl methacrylates and amino compounds such the interpolymer of vinyl pyrrolidone, stearyl methacrylate, lauryl methacrylate and butyl methacrylate. These detergent-dispersant additives are usually present in the lubricating oil in concentrations between 0.1 and 10 wt. percent.

The most commonly used corrosion inhibitor and antioxident lubricating oil compositions is a divalent metal alkyl dithiophosphate resulting from the neutralization of a P S -alcohol reaction product with a divalent metal or a divalent metal oxide. Barium and zinc alkyl dithiophosphates are the most widely used oxidation and corrosion inhibitors. Metal dialkyl dithiophosphates are usually present in the lubracting oil in a concentration of between 0.1 and 3.0 wt. percent.

As heretofore stated the present invention is also applicable to grease compositions containing the poly-pphenylene extreme pressure additive contemplated herein. The grease base is prepared by standard means, for example, by the addition to the aforedescribed mineral synthetic lubricating oil of thickening agents such as hydrocarbon soluble metal soaps or salts of higher fatty acids, for example, lithium stearate, calcium stearate, and aluminum naphthenate. One of. the best metal soaps is lithium 12-hydroxy stearate. It is often prepared in situ by heating a mixture of methyl-IZ-hydroxy stearate and lithium hydroxide in the lubricating oil at elevated temperature, e.g., 100 to 200 C. The contemplated manufacture of grease bases and their com-positions are further described in the book by Bonner, Manufacture and Application of Lubricating Greases, Reinhold Publishing Corp., New York, 1954. The metal soap ingredient normally constitutes between about 5-15 wt. percent of the grease composition and constitutes a major part if not all of the total base oil thickening component.

The greases may also contain various supplementary additives of the usual type such as corrosion inhibitors and oxidation inhibitors. Specific examples of oxidation inhibitors contemplated are the amine type such as phenyl-alpha-naphthylamine, diphenylamine and tetr'amethyldiaminodiphenyl methane. Particular examples of corrosion inhibitors contemplated herein are the long chain olefinic unsaturated polyamines such as n-oleyl propylenediamine. These oxidation inhibitors and corrosion inhibitors are normally each present in the grease in an amount of between about 1 and 5 wt. percent.

In the method embodiment of the invention the metal surface is lubricated by contacting said metal surface with the dry, finely divided poly-p-phenylene polymer or the aforementioned lubricating oil and grease compositions containing said poly-p-phenylene in a manner well known in the art to form a lubricant coating on said surface. Examples of metal surfaces for lubrication are automobile engine surfaces, wheel bearing surfaces and lock mechanism surfaces. Lock mechanisms are particularly adaptable to lubrication by the dry, finely divided poly-p-phenylene which is graphite-like in its lubrication properties.

The following examples further illustrate the invention but are not to be taken as limitations thereof.

3 Example 1 This example illustrates the preparation of the polyp-phenylene extreme pressure agent utilized in the compositions of the invention.

A slurry of 396 grams (3.0 mols) of aluminum chloride powder and 399 grams (3.0 mols) of anhydrous cupric chloride powder were refluxed with 1500 mls. of dry benzene at C. for a period of two hours. The slurry was filtered and the solid was washed repeatedly with an aqueous hydrochloric acid solution until the filtrate was colorless and then washed with water until neutral. The brownish solid was dried in vacuo to give about 80 grams of poly-p-phenylene solid.

Poly-p-phenylene solid of the type prepared above gave the following analysis:

TABLE I Description: Results Infrared bands, cm. 805 (strong), 765

(weak), 695 (weak).

X-ray d-spacing, A. 450, 3.90, 2.10, 2.02. Elemental analysis, wt.

percent:

Carbon 91.4.

Hydrogen 5.2. Impurity 3.4. Carbon/hydrogen atomic ratio 1.46.

Color Brown-black. Solubility Insoluble all solvents. Electrical resistance,

ohm-cm. 3.5 X10 Average molecular weight 3000.

The Impurity in above Table I is composed primarily of inorganic copper and aluminum compounds entrapped by the polymer molecules as well as a minor amount (e.g., 0.1 wt. percent) of chlorine substituent in the polymer itself.

Example II This example. illustrates the extreme pressure properties imparted to mineral lubricating oil compositions by the poly-p-phenylene solid polymer of the type prepared in Example I.

Poly-p-phenylene of the type prepared in Example 1 was ground to a particle size averaging about 17 microns and incorporated in varying amounts in the following described base oil composition at 25 to 30 C. under mixing conditions. For comparative purposes two additional lubricating oil compositions were prepared, one containing no extreme pressure additive and the other containing the well known molybdenum sulfide extreme pressure additive. The molybdenum sulfide employed was of an average 2 micron particle size. The base lubricating oil composition employed was designated as Base Oil A and consists of 99 wt. percent of a mineral lubricating oil having a viscosity of 100 F. of about 310 SUS, and containing 1 wt. percent of an interpolymer of vinyl pyrrolidone, stearyl meth acrylate, lauryl methacrylate and butyl methacrylate in a respective weight ratio of 8:30:50: 12.

The prepared lubricating oil compositions were subjected to the Mean Hertz Load Test and the 4-Ball Wear Test. The Mean Hertz Load Test is described in US. Patent No. 2,600,058 and the 4-Ball Wear Test is described in Us. Patent No. 3,050,466. These two tests measure the relative extreme pressure properties of a lubricating oil composition. In the Mean Hertz Load Test the greater the weight load that can beapplicd the better the extreme pressure of the lubricant material tested. In the 4-Ball Wear Test the smaller the average scar diameter on the ball the better the extreme properties of the tested lubricant. The test results are reported below in Table 11.

TABLE II As can be seen from the foregoing, the poly-p-phenylene solid polymer imparts extreme pressure properties to lubricating oils, comparable to the well known molybdenum disulfide extreme pressure agent.

Example III This example illustrates the effectiveness of the poly-pphenylene as extreme pressure additive in a synthetic lubricating oil.

The synthetic lubricating oil employed was polydimethylsiloxane having a viscosity of 1000 cs. at 77 F. The poly-p-phenylene containing siloxane lubricating oil composition was formed by grinding the solid poly-pphenylene of the type prepared in Example I to an average about 17 micron particle size and adding the polyphonylene polymer with mixing to the siloxane fluid at 25 to 30 C. For comparative purposes two additional compositions were tested, namely, the polydimethylsiloxane fluid per se and the siloxane fluid containing molybdenum disulfide of about 2 to 7 microns average particle size. The three compositions, namely, the pure silicone fluid, the poly-p-phenylene and molybdenum disulfide containing silicone fluids were subjected to the 4-Ball Wear Test. The test results are reported below in Table III.

TABLE III 4-B all Wear Test Average Scar Material Dispersed in Silicone Fluid Amount Dispersed Material, wt.

Percent Diameter, mm.

Poly-p-phenylene 25 0. 846 Molybdenum disulfide 25 0. 932 N one 0 1. 359

As can be seen from the foregoing table, the poly-pphenylene containing synthetic fluid has a better load carrying capacity than the fluid without any extreme pressure additive and the silicone fluid containing the well known molybdenum disulfide extreme pressure additive.

Example IV This example illustrates the effectiveness of the poly-pphenylene as extreme pressure additive in grease compositions.

The two base grease compositions employed are of the following formulation:

TABLE IV [Grease A] Ingredients: Wt. percent Mineral oil of about 185 SUS vise. at 100 F. 74

1 React at about 150 to 200 C. during preparation of Greases A and B to form lithium 1'2-hydr0xy stearate with the methyl alcohol byproduct being distilled off.

To Greases A and B there was added poly-p-phenylene of the type prepared in Example I in an average particle size of about 8 microns under mixing conditions. For further comparison Grease A and Grease B were tested per se, without any addition of extreme pressure agents. The tests utilized were the Mean Hertz Load Test and the the Falex Wear Test. The Mean Hertz Load Test was previously described and a description of the Falex Wear Test can be found in US. Patent No. 2,796,402. The test results are reported below in Table V.

TABLE V Composition Mean Hertz Falex Test Load, kg.

G rease A 19 Failed. Grease A+5 wt. percent; poly-pphenylene 24 Passed. Grease B 22 Failed in 2 minutes. Grease B+5 wt. p ent pol pphenylene 29 Failed in 1 hour.

As can be seen from the foregoing table the poly-pphenylene imparts extreme pressure properties to grease compositions.

Example V This example illustrates the friction reducing properties of the poly-p-phenylene when employed as a dry lubricant.

The test employed was run on a standard Four Ball Wear Tester except the ball pot which normally contains the three lower balls was replaced with a disc holder in which three silver discs are placed. The discs are positioned by the recesses in the holder so that they contact the rotating ball at the points as when the lower three balls are used for test specimens.

The lubricant to be tested is placed in test holder in sufiicient amount to cover the silver discs and the upper ball is engaged with the discs. The disc holders then were rotated at 600 r.p.m. under a 10 kilogram load and the coeflicient of friction was measured at the end of an hour operation period. The higher the coeflicient of friction the poorer the friction reducing properties. Three materials were tested. They were the polyp-phenylene of the type prepared in Example I and two known comparative dry lubricants, molybdenum disulfide and polytetrafluoroethylene (Teflon). The test results are reported below in Table VI.

TABLE IV Material tested: Coeflicient of friction Poly-p-phenylene 0.212 Molybdenum disulfide 0.161 Teflon 0.237

As can be seen the poly-p-phenylene has essentially the same order of coeflicient of friction as the well known dry lubricants of molybdenum disulfide and Teflon (polytetrafluoroethylene) We claim:

1. A lubricant composition comprising a major portion of an oleaginous material selected from the group con sisting of mineral lubricating oil, polydimethylsiloxane having a viscosity of between about 50 and 1000 SUS at F., and a lubricating mineral oil base grease and an amount sufficient to impart extreme pressure properties to said composition of a finely divided poly-p-phenylene solid of the formula:

Q Q Q L J.

where n is an average integer between about 38 and 200. 2. A composition in accordance with claim 1 wherein said poly-p-phenylene is present in an amount between about 0.5 and 30 wt. percent and of an average particle size of between about 2 and 100 microns.

3. A lubricating oil composition comprising between about 70 and 99.5 wt. percent mineral lubricating oil of an SUS viscosity between about 50 and 10,000 at 100 F. and

between about 0.5 and 30 wt. percent of a poly-p-phenylene solid polymer of the formula:

/ .E l L ,1.

where n is an average integer between about 38 and 200,

said polymer having an average particle size of between about 2 and 100 microns.

4. A grease composition comprising a major portion of a mineral lubricating oil having an SUS viscosity at 100 F. of between about 50 and 10,000, a grease forming amount of a metal soap, and between about 0.5 and 30 wt. percent of poly-p-phenylene solid polymer of the formula:

a viscosity of about 1000 centistokes at 77 F. and between about 0.5 to 30 wt. percent of a poly-p-phenylene solid polymer of the formula:

where n is an average integer between about 38 and 200 and said poly-p-phenylene being of a particle size between about 2 and 100 microns.

References Cited UNITED STATES PATENTS 2,916,452 12/1959 Givens et al. 252-4l 3,291,732 12/1966 Spilners et a1. 252-28 3,291,733 12/1966 McCarthy et a1. 262-28 2,121,326 6/1938 Pevere 252-59 2,729,691 1/1956 De Pree 252-50 X 2,837,482 6/1958 Agens 252-421 X 2,990,419 6/1961 Nitzsche et al. 252-496 X 3,057,801 10/1962 Wilgus 252-59 3,066,101 11/1962 Wilgus 252-59 OTHER REFERENCES Duomeens, product booklet of Armour Chemical Div., 1355 W. 31st St., Chicago, Ill. (1956).

Kovacic et al.: Polymerization of Benzene to p-Polyphenyl by Aluminum Chloride-Cupric Chloride, J.

5 American Chem. Soc., 85, pages 454-458 (1963).

DANIEL E. WYMAN, Primary Examiner.

PATRICK P. GARVIN, Examiner. 

4. A GREASE COMPOSITION COMPRISING A MAJOR PORTION OF A MINERAL LUBRICATING OIL HAVING AN SUS VISCOSITY AT 100* F. OF BETWEEN ABOUT 50 AND 10,000, A GREASE FORMING AMOUNT OF A METAL SOAP, AND BETWEEN ABOUT 0.5 AND 30 WT. PERCENT OF POLY-P-PHENYLENE SOLID POLYMER OF THE FORMULA:
 5. A GREASE COMPOSITION IN ACCORDANCE WITH CLAIM 4 WHEREIN SAID METAL SOAP IS LITHIUM 12-HYDROXYSTEARATE AND ALSO INCLUDED IN SAID COMPOSITION IS AN OXIDATION INHIBITING AMOUNT OF PHENYL-ALPHA-NAPHTHYLAMINE AND A RUST INHIBITING AMOUNT OF N-OLEYLPROPYLENE DIAMINE. 